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TLS Online TPP Program

#Question id: 3298

Which of the following is incorrect statement?

#Section 3: Genetics, Cellular and Molecular Biology

  1. Natural selection is blind to the future: there is no consiousness or "purpose" behind it.

  2. Artificial selection has a conscious element driving the evolution of a species for some purpose

  3. Gene flow tends to homogenize allele frequencies between two or more populations that is the exact opposite of drift

  4. Alone, mutation is considered the strongest force of evolution

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TLS Online TPP Program

#Question id: 14263

#Section 5: Bioprocess Engineering and Process Biotechnology

The BOD5 value of a waste-water feed stream to an activated-sludge unit is S0 = 300 mg/l, and the effluent is desired to be S = 30 mg/l. The feed flow rate is F = 2× 10^7 l/day. For the recycle ratio of α = 0.5 and a steady-state biomass concentration of X = 5 g/l, Use the following kinetic parameters:

 
calculate Biomass concentration in recycle (Xr).
TLS Online TPP Program

#Question id: 14264

#Section 5: Bioprocess Engineering and Process Biotechnology

The BOD5 value of a waste-water feed stream to an activated-sludge unit is S0 = 300 mg/l, and the effluent is desired to be S = 30 mg/l. The feed flow rate is F = 2× 10^7 l/day. For the recycle ratio of α = 0.5 and a steady-state biomass concentration of X = 5 g/l, Use the following kinetic parameters:

 
calculate Hydraulic residence time
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TLS Online TPP Program

#Question id: 14265

#Section 5: Bioprocess Engineering and Process Biotechnology

For the activated-sludge, the specific growth rate of cells is given by 


 

The following parameter values are known: F = 500 l/h, α = 0.4, ɣ = 0.1, Xe = 0, V = 1500 l, Ks = 10 mg/l, µm = 1 h-1 , kd = 0.05 h-1 , S0 = 1000 mg/l, Y M X/S = 0.5 g dw/g substrate. Calculate the substrate concentration (S) in the reactor at steady state. -------------------------
TLS Online TPP Program

#Question id: 14266

#Section 5: Bioprocess Engineering and Process Biotechnology

For the activated-sludge, the specific growth rate of cells is given by 


 

The following parameter values are known: F = 500 l/h, α = 0.4, ɣ = 0.1, Xe = 0, V = 1500 l, Ks = 10 mg/l, µm = 1 h-1 , kd = 0.05 h^-1 , S0 = 1000 mg/l, Y M X/S = 0.5 g dw/g substrate.. Calculate the cell concentration in the reactor. 
TLS Online TPP Program

#Question id: 14267

#Section 5: Bioprocess Engineering and Process Biotechnology

In a trickling biological filter, the BOD value of the feed stream is S0i = 500 mg/l with a feed flow of F = 103 l/h. The effluent BOD value is desired to be S0 = 10 mg/l. The following kinetic parameters for the biocatalysts are known: rm = 20 mg/S/l .h and Ks = 200 mg S/l. The biofilm thickness is L = 0.1 mm. The cross-sectional area of the filter is A = 2 m2 , and the biofilm surface area per unit volume of the bed is a = 500 cm2 /cm3 . Assume that dissolved oxygen is the rate-limiting substrate and the diffusion coefficient of oxygen is DO2 = 2 × 10-5 cm2 /s. Determine the required height of the bed. You can assume first-order bioreaction kinetics?

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TLS Online TPP Program

#Question id: 14268

#Section 5: Bioprocess Engineering and Process Biotechnology

An activated-sludge waste treatment system is required to reduce the amount of BOD5 from 1000 mg/l to 20 mg/l at the exit. The sedimentation unit concentrates biomass by a factor of 3. Kinetic parameters are µm = 0.2 h-1 , Ks = 80 mg/l, kd = 0.01 h-1 , and Y M X/S = 0.5 g MLVSS/g BOD5. The flow of waste water is 10000 l/h and the size of the treatment basin is 50,000 l. What is the value of the solids residence time?